Accelerator physics codes

A charged particle accelerator is a complex machine that takes elementary charged particles and accelerates them to very high energies. Accelerator physics is a field of physics encompassing all the aspects required to design and operate the equipment and to understand the resulting dynamics of the charged particles. There are software packages associated with each such domain. A broader index of existing and historical accelerator simulation codes is located at [1]

The interactions between the particles in the beam can have important effects on the behavior, control and dynamics. Collective effects take different forms from Intra-Beam Scattering (IBS) which is a direct particle-particle interaction to wakefieds which are mediated by the vacuum chamber wall of the machine the particles are traveling in. In general, the effect of direct particle-particle interactions is less with higher energy particle beams. At very low energies, this space charge effect has a large effect on a particle beam and also becomes hard to calculate. The above simulation do not handle low energy space charge effects.

The self interaction (e.g. space charge) of the charged particle beam can cause growth of the beam, such as with bunch lengthening or intrabeam scattering, or it may cause an instability and associated beam loss. Typically the Poisson equation is solved at intervals during the tracking using Particle-in-cell algorithms. Many scientists have written special purpose codes to compute these growth values and instability thresholds. Codes include

An important class of collective effects may be summarized in terms of the beams response to an "impedance". An important job is thus the computation of this impedance for the machine. Codes for this computation include

To control the charged particle beam, appropriate electric and magnetic fields must be created. There are software packages to help in the design and understanding of the magnets, RF cavities, and other elements that create these fields. Codes include

Given the variety of modelling tasks, there is not one common data format that has developed. For describing the layout of an accelerator and the corresponding elements, one uses a so-called "lattice file". There have been numerous attempts at unifying the lattice file formats used in different codes. One unification attempt is the Accelerator Markup Language, and the Universal Accelerator Parser.[34] Another attempt at a unified approach to accelerator codes is the UAL or Universal Accelerator Library.[35]

The file formats used in MAD may be the most common, with translation routines available to convert to an input form needed for a different code. Associated with the Elegant code is a data format called SDDS, with an associated suite of tools. If one uses a Matlab-based code, such as Accelerator Toolbox, one has available all the tools within Matlab.

There are many applications of particle accelerators. For example, two important applications are elementary particle physics and synchrotron radiation production. When performing a modeling task for any accelerator operation, the results of charged particle beam dynamics simulations must feed into the associated application. Thus, for a full simulation, one must include the codes in associated applications. For particle physics, the simulation may be continued in a detector with a code such as Geant4.

For a synchrotron radiation facility, for example, the electron beam produces an x-ray beam that then travels down a beamline before reaching the experiment. Thus, the electron beam modeling software must interface with the x-ray optics modelling software such as SRW,[36] Shadow,[37] McXTrace,[38] or Spectra.[39] Bmad,[5] is an exception since it can model both X-rays and charged particle beams. The x-rays are used in an experiment which may be modeled and analyzed with various software, such as the DAWN science platform.[40]